The conflicts to control collective resources within an area of Dogana (Southern Tuscany, 14th-15th c.) The paper aims to analyze the conflicts in acces to collective resources(pastures) at local level, focusing on their relation with the State-building process. Southern Tuscany was conquered and became part of the State of Siena during the 14th-15thc. It was reorganized through the Dogana dei Paschi of Siena, a fiscal institution in charge of managing transhumant flows in that area. The related take over of collective rights of pasturages and common land carried on by Siena in 1353-1419 lead to new levels of conflict for the management of commons. As a consequence, it created new asymmetric relations between the communities, the city-commune and the transhumant shepherds, usually damaging, the formers. Through the analysis of the public archival records of Siena and of those of some communities it is possible to show to what extent this process was strong and ground-breaking in plundering and re-distributing collective resources. The paper aims, furthermore,to suggest applying both the micro-historial as well as the new-institutional approach to improve our understanding of socio-economic dynamics of commons within similar case-studies